Origins of Scottish measures
In Scotland, as in much of western Europe, weights
and measures were based mainly on the Imperial
system of measurement, used in the Roman Empire.
After the fall of the Empire, standard measures
diverged in different parts of Europe, so that,
by the early Middle Ages Scottish measures differed
from the measures in England and in other parts
of Europe. Imperial weights were divided into
troy and avoirdupois. Troy
weight (the origin of the word troy is
obscure but may come from the French town of Troyes)
is used by silversmiths to measure gold, silver
and gemstones, and was used by apothecaries to
measure small amounts of chemicals. Each Troy
pound was divided into 12 ounces. Avoirdupois
weight (from the French meaning 'to have weight')
was used to measure bulkier goods. The
avoirdupois pound had 16 ounces, which
allowed for easier calculations into quarters.
Locally weights and measures were regulated mainly
by burghs, where the public weighing machine,
the tron (from the old French tronel
or troneau, meaning 'balance'), was one
of the key places of the burgh. The street where
it was situated was often known as the Trongate
(gate meaning 'street', from the middle English
gate or Old Norse gata), and the Tron
was often the site of public meetings and punishments,
such as the pillory. In Scotland tronweight meant weight according to a local
standard.

Standardization
From the twelfth century onwards the Scottish
parliament attempted to standardize local measures,
but national standards were not imposed until
1661, when a parliamentary commission in Scotland
decided that certain burghs in Scotland would
be responsible for keeping standards: Edinburgh
kept the 'ell' for linear measure, Linlithgow
the 'firlot' for dry measure, Lanark the 'troy
stone' for weight, and Stirling the 'pint' (or
'joug') for liquid capacity. The Act of Union
introduced English measures into Scotland in 1707,
but this meant that English and Scottish measures
were now used, and historians must be very careful
when dealing with quantities described in documents
in the eighteenth and early-nineteenth centuries.
Scottish weights and measures gradually disappeared
only after the Imperial Weights and Measures Act
1824 (local variations were still in use in some
areas in the 1840s).

Metric (SI) system
The efficacy of decimalization in measurement
and money had been apparent in European intellectual
circles since the late sixteenth century. In 1790
the French National Assembly enforced a system
devised by the French Academy of Science, which
based measuring units on invariable quantities
in nature, and made multiples and divisions of
the units decimal. This metric system took its
name from the unit for linear measure (the metre)
and began to be adopted by many countries throughout
the world. In 1960 the system was officially named
the Système International d'Unités,
or SI for short. The Metric Weights and Measures
Act 1864 introduced metric units to the UK, but
these were not compulsory. From 1868 onwards attempts
were made in parliament to abolish Imperial measure,
but it was not until 1969 that a gradual process
of phasing out Imperial measures was begun in
the UK. Since 1995 most pre-packaged goods have
been sold in metric units, and from 1 January
2000 it has been illegal to sell loose products
(such as vegetables, fruit, cheese, etc) by pounds,
ounces, pints or gallons (with the exception of
draught beer, which is still sold in pints).